libbpf: Verify section type in btf_find_elf_sections

JIRA: https://issues.redhat.com/browse/RHEL-78203

commit 8582d9a
Author: Ihor Solodrai <ihor.solodrai@linux.dev>
Date:   Thu Apr 10 11:28:23 2025 -0700

    libbpf: Verify section type in btf_find_elf_sections
    
    A valid ELF file may contain a SHT_NOBITS .BTF section. This case is
    not handled correctly in btf_parse_elf, which leads to a segfault.
    
    Before attempting to load BTF section data, check that the section
    type is SHT_PROGBITS, which is the expected type for BTF data.  Fail
    with an error if the type is different.
    
    Bug report: libbpf/libbpf#894
    v1: https://lore.kernel.org/bpf/20250408184104.3962949-1-ihor.solodrai@linux.dev/
    
    Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
    Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
    Link: https://lore.kernel.org/bpf/20250410182823.1591681-1-ihor.solodrai@linux.dev

Signed-off-by: Viktor Malik <vmalik@redhat.com>

Author: viktormalik

tools/lib/bpf/btf.c

@@ -1148,6 +1148,12 @@ static int btf_find_elf_sections(Elf *elf, const char *path, struct btf_elf_secs
 		else
 			continue;
 
+		if (sh.sh_type != SHT_PROGBITS) {
+			pr_warn("unexpected section type (%d) of section(%d, %s) from %s\n",
+				sh.sh_type, idx, name, path);
+			goto err;
+		}
+
 		data = elf_getdata(scn, 0);
 		if (!data) {
 			pr_warn("failed to get section(%d, %s) data from %s\n",